1. Field of the Invention
This invention relates to a marine water pump, and more particularly to an improved drive shaft for a marine water pump.
2. Description of the Related Art
A marine water pump is used to recirculate coolant or salt water through the cylinder block of a marine engine. The water pump is equipped with a drive shaft connected to the water pump impeller on one end thereof and a shaft tang on the opposite end connected to an accessory drive. The accessory drive includes a drive slot for engagement of the shaft tang when the water pump is fixedly mounted to the accessory drive housing. As a consequence, the impeller is rotated by the drive shaft via the rotational motion of the accessory drive.
Referring to FIGS. 1 and 1A, a prior art marine water pump drive shaft is shown and comprises a first end 10 having a slot 10A, a second end 20 having a generally rectangular pump shaft tang 20A extending outward from a rounded elongate shaft 15, the elongate shaft 15 being disposed between first end 10 and second end 20. Pump shaft tang 20A includes a flat surface 20A 1 and 20A2 that are stepped down from rounded elongate shaft 15. Slot 10A of first end 10 is adapted for coupling to the impellor of a water pump and pump shaft tang 20A is adapted for coupling to a marine accessory drive.
The marine water pump drive shaft of FIGS. 1 and 1A is prone to failure in the field and has shown to be an excessive maintenance burden for removal and replacement. In a typical environment, such as a marine vessel or boat, a failed marine pump shaft must be replaced in a short period of time. Often is the case when a pump may fail during a storm or unsteady seas requiring the pump to be changed out. It is imperative that the pump be changed out expeditiously to get the marine vessel engine underway to a safer environment. The shaft of FIGS. 1 and 1A is prone to failure due to an inferior pump shaft tang 20A design. Furthermore, the prior art pump shaft is hard to replace when failed due to its dimensioning and inability to be aligned correctly within a marine water pump during maintenance.